globulin,
You do not necessarily have to publish to have a meaningful research experience, but publications lend credibility to your research. There are many people who, like you, have done a year (or years) of research and don't publish--this depends as much on the type of research and your Principle Investigator as it does on your hard work. You may still get lucky, and your research may be published down the road (this happened to me). If you don't publish, you can also present your research at conferences.
As far as research in medical school, there are many opportunities at most schools. The most convenient time is the ~3 months between first and second year. You can also use elective time during 3rd and 4th years for research--at my school, this could be about 6 months worth. I also know a number of students who took an additional year to work on a research project (or other endeavors) and this is a great option if you're really motivated. If you're super interesting in research and interested in an academic career, you can always consider switching into an MD/PhD program. I've heard you can often get funding for the remainder of you schooling if you do this (but not for the years before you switch).
You can also do clinical research projects at almost any time--ask a doctor in a field you're interested in if they have any clinical research projects you could help with. Many of these will involve a lot of sorting through charts, etc.
Hope this helps! 🙂